James Brown is a big influence yes but to say it wouldn't exist without him is madness. Look at the first superstar rap act, Run DMC. They didn't sample James Brown until their 4th album, when they were already superstars. So what were the doing for the first 3 albums that made them legends? Yes break beats are the foundation of hip hop. But you do understand it wasn't just James Brown break beats being used right?
James Brown created the sonic foundations that hiphop would be born out of. Take for example the Aerosmith drumbreak that they sampled
.
.
.
Those type of drum grooves never existed prior to James Brown's creation of Funk. See
Once James invented the formula
drumming changed across genres from 1965 ->on...
even the white Rockers picked up on the Funk
.
.
so even when you weren't sampling actual James Brown songs, you were sampling music that was born of his Funk vocab/formula